docs: def serialize(self, items, default_flow_style=False):
          """Does the inverse of config parsing by taking parsed values and
          converting them back to a string representing config file contents.
  
          Args:
              default_flow_style: defines serialization format (see PyYAML docs)
          """
  
          # lazy-import so there's no dependency on yaml unless this class is used
          yaml = self._load_yaml()
  
          # it looks like ordering can't be preserved: http://pyyaml.org/ticket/29
          items = dict(items)
          return yaml.dump(items, default_flow_style=default_flow_style)